Stabilization of unsaturated organic material-sulfur dioxide resins with elemental sulfur or inorganic sulfides



Patented June 1 0, 1952 OFFICE STABILIZATION F UN SATURATED 0R- GANIO MATERIAL-SULFUR DIOXIDE RESIN S WITH ELEMENTAL SULFUR OR INORGANIC SULFIDES Willie W. Crouch and John F. Howe, Bartlesville,

0kla., assignors to Phillips Petroleum Company, a corporation of Delaware No Drawing. Application January 31, 1951, Serial No. 208,853

18 Claims. 1

This invention relates to a method for producing thermally stable olefin-sulfur dioxide resins. In one aspect this invention relates to incorporating elemental sulfur or inorganic sulfides in an olefin-sulfur dioxide resin. In another aspect this invention relates to a process of producing a thermally stable olefin-sulfur dioxide resin that is free of unpleasant odors. In still another aspect this invention relates to a method of shortstopping the polymerization of an olefin-sulfur dioxide resin so that a thermally stable resin results. In still another aspect this invention relates to a method for shortstopping the polymerization of an olefin-sulfur dioxide resm.

Olefin-sulfur dioxide resins often cannot be employed satisfactorily for the production of molded articles because of their limited thermal stability. On being exposed to elevated temperatures, the original glass-like resin evolves sulfur dioxide, unsaturated organic compounds and various volatile decomposition products of unpleasant odor, expanding into a porous, voluminous mass having a puffy structure.

Various so-called stabilizing agents have been suggested as addition compounds for the olefinsulfur dioxide resins. These addition compounds include organic solvent liquids and vapors, acry1- c acid esters, vinyl acetate and acylating agents which supposedly act to remove occluded sulfur dioxide. When heated to the elevated temperatures necessary for injection molding operations, such as 300 F. or higher, these stabilizing agents become essentially ineffective and the resins containing them are substantially as unstable as in their absence. More recently it has been disclosed that sulfhydryl compounds such as mercapto ethanol, thio glycollic acid, benzyl mercaptan and the like impart thermal stability to said resins. However, these compounds are malodorous and are undesirable in commercial products. In addition those compounds are often not readily available.

It has now been discovered that olefin-sulfur dioxide resins can be rendered highly resistant to thermal decomposition when sulfur or an in,- organic sulfide is incorporated therein as a stabilizing agent. When added to an olefin-sulfur dioxide resin according to the method of our invention, sulfur or an inorganic sulfide imparts excellent thermal stability to saidresins and in some instances completely inhibits their decomposition at molding temperatures.

According to this invention there is. provided a process for the production of. a. stable olefinsulfur dioxide resin which comprises the step of adding to the said resin, sulfur or an inorganic sulfide during the polymerization reaction or after the reaction has been completed. When added to the polymerization reaction the sulfide is admixed with the acid latex. Preferably the sulfide is added to a resin when said resin is dispersed in an aqueous medium containing sufficient sulfur dioxide to produce a pH of 5 or lower. When added after the completion of the reaction the sulfur or sulfide can be incorporated into the resin by simple admixture or by precipitation or other means, whether physical or chemical.

Both soluble and insoluble sulfides are operable. The water soluble compounds are generally preferred and provide better, stabilization than the water insoluble compounds. Typical sulfides applicable to the method of the present invention include hydrogen sulfide, sodium, zinc, barium, cadmium, tin, and ammonium sulfides. Sodium hydrosulfide, potassium hydrosulfide, ammonium hydrosulfide and the like are also applicable.

In order to effect the desired degree of stabilization from 0.05 to 10, preferably 0.5 to 5 weight per cent, based on the weight of the resin, of sulfur or inorganic sulfide is incorporated in the molding composition employed.

Sulfur can be incorporated into the olefinsulfur dioxide resin in a number of ways, the important factor being that said sulfur be thoroughly and intimately mixed with the resin. Thus, for example, finely-divided sulfur can be added to the finely-divided, dry resin by distributing the desired quantity evenly therein by means of a suitable mixing device. Sulfur can also be added as an aqueous slurry to the finelydivided, dry resin and thoroughly mixed therewith followed by suitable removal of water. It has usually been preferred to add an aqueous slurry of sulfur to a dispersion of the resin in the latex in which it has been prepared and both the resin and admixed sulfur separated therefrom simultaneously. When operating in this preferred manner, sulfur is added to a resin latex produced in: an emulsion polymerization system just after the polymerization has been completedv and excess sulfur dioxide vented from the reactor. Addition of sulfur can also be made at other points in the manipulative process as will be apparent to one skilled in the art. Advantage can be taken of any sulfur which may occur in situ in the latex or resin. Sulfur is applicable for the stabilization of olefin-sulfur dioxide resins produced by any method such as polymerization in excess sulfur dioxide or acetone or other suitable solvent. employ resins produced by emulsion polymeriza- It has usually been preferred to tion methods, more particularly resins produced by the method disclosed in co-pending application Serial No. 8,755, filed February 16, 1948, by Willie W. Crouch and Ernest W. Cotten. Organic compounds which enter into the formation of such resins include mono-olefins, cyclo-olefins, substituted aliphatic olefins such as styrene, diolefins such as butadiene, isoprene, cyclohexadiene, and. the like, acetylenes and polyfunctional unsaturated compounds such as allyl alcohol, Vinyl acetate, allyl ethyl ether, o-allylanisole, o-allylphenol, p-bromoallylbenzene, methyl undecylenate, undecylenyl alcohol, undecylenic acid, etc. The process comprises reacting the unsaturated compound and sulfur dioxide in aqueous emulsion in the presence of suitable catalysts and emulsifying agents.

To accomplish the desired results of the present invention, when sulfides are used instead of sulfur, the addition of the sulfide to the resin is preferably made when the resin is in the acid latex state. This is most conveniently done after polymerization is completed and excess sulfur dioxide has been vented from the reactor. At this point the latex contains dissolved sulfur dioxide and is highly acidic.

It has also been discovered, according to this invention, when sulfur or a sulfide is added to an olefin-sulfur dioxide polymerization recipe before the reaction has been allowed to go to completion, that the polymerization is stopped. Thus the additives of the present invention provide a means for controlling the degree of conversion in an olefin-sulfur dioxide polymerization reaction as well as a means for the stabilization of such resins as are thus prepared.

PREPARATION OF l-BUTENE-SULFUR DIOXIDE RESIN An olefin-sulfur dioxide resin was prepared using the following emulsion recipe in a stainless steel autoclave.

Parts by Weight Commercial l-butene 57.7 Sulfur dioxide 38.3 Water 180 Ammonium nitrate 0.5 MaprofixMM 0.6

The commercial l-butene had the following composition:

M01 per cent l butene 63.2 2-butene-cis 1.0 2-butene-trans 12.5 n-Butane 13.4 Isobutane 4.6

3 Isobntylene 3.6 Butadiene 0.7

Example I Varying amounts of powdered sulfur in the form of a slurry in water were added to portions of acid latex prepared in the manner described above and thoroughly commingled therewith. The latex was then stripped of dissolved sulfur dioxide and coagulated with an aqueous solution Per Cent Loss in Weight at End of 1 Hours Heating at 325i2 F.

Sample I:

Control 3. 4 0.5 11.4 0. 1% sulfur, based on weight of dry resin 1.40 3.1 4. 8 0.3% sulfur, based on weight of dry resin 0.70 1. 24 3.0 0.5% sulfur, based on weight of dry resin 0.55 0.99 2.70

(Latices coagulated with methanol) Sample II Control 4. 6 7.6 12.3 2.0% sulfur, based on weight of dry resin 0 0.02 0. 53

(Latex coagulated with magnesium sulfate) Example II To demonstrate the operability of powdered sulfur as a thermal stabilization agent when added to a dry resin, the following run was made. The resin was prepared from l-butene 1 according to the method described before. Sulfur was intimately com-mingled with the dry resin by mixing. Results of thermal stability tests are recorded below.

Per Cent Loss in Weight at End of .1 Hours Heating at 325 F.

0.5% sulfur added to dry resin 0.99 1. 71 3.10 Control 5. 0 8. 2 15. 4

(Resins coagulated from latex with methanol) The results show that the addition of powdered sulfur to a finely divided dry resin effectively reduces thermal decomposition of a typical olefin-sulfur dioxide resin.

Example III A further series of tests was made wherein hydrogen sulfide was runinto acid latex prepared in the manner described before to provide varying amounts of free sulfur. Results of thermal decomposition tests made on the resins re- 1 Commercial butene as described herein.

covered from treated latices and on untreated control are recorded in the following table.

Per Cent Loss in Weight at End of :t Hours Heating at 325 F.

Control 3. 4 6. 5 i ll. 4 0.5% sulfur. Hydrogen sulfide added to acid latex to provide 0.5% sulfur based on weight of dry resin 0. 57 1.05 2.0 1.0% sulfur. Hydrogen sulfide added to acid latex to provide 1.0% sulfur based on weight of dry resin 0. 37 0. 72 l. 95

The results show that hydrogen sulfide substantially reduces thermal decomposition of a l-butene sulfur dioxide resin when added to the sulfur dioxide containing latex thereof. Results closely parallel those provided by the addition of a corresponding amount of powdered sulfur to an acid latex.

Example IV Sodium sulfide was added to an acid latex of a l-butene -sulfur dioxide resin prepared as described before. Results of thermal decomposition tests made on the resin recovered from the treated sample and an untreated control are recorded in the following table.

Per Cent Loss in Weight at End 01 2: Hours Heating at 325 F.

Control 5. s 9. 7 16.9 2% sodium sulfide based on weight of dry resin. Sodium sulfide added as aqueous solution to acid latex 0.59 1.09 2. 41

(Latlefxt coagnlated with magnesium su a e The results show that sodium sulfide appreciably reduces thermal decomposition of a typical olefin-sulfur dioxide resin when added to the acid latex of said resin.

Example V Latex prepared according to the procedure described before was employed in the following tests wherein various sulfides were added to the acid latex in an amount equal to 2% of the Weight of the dry resin. Results of thermal decomposition tests made on the treated resins and an untreated control are recorded in the following table.

Per Cent Loss in Weight at End of 1 Hours Heating at 325 F.

Control 4. 4 7. 2 13.1 2% zinc sulfide based on weight oi dry rosin. Zinc sulfide added to acid latex as wetted powder 1. 29 2. 44' 5.3 2% barium sulfide based on we1ght of dry resin. Barium sulfide added to acid latex as an aqueous solution-.. 0.21 0. 55 1. 49

2% cadmium sulfide based on weight of dry resin. Cadmium sulfide added to acid latex as a wetted powder 2% ammonium sulfide based on weight of dry resin. Ammonium sulfide added to acid latex as an aqueous solution.--

2% stannous sulfide based on weight of dry resin. Stennous sulfide added to acid latex as wetted powder (Latices coagulated with methanol) 1 Commercial butcne as described herein.

Example VI A butene -l-sulfur dioxide resin latex containing dissolved sulfur dioxide, was prepared as described before. Samples of the latex were treated with an aqueous dispersion of sodium tetrasulfide (NazSi), stripped of sulfur dioxide, coagulated, washed and dried. Results of thermal decomposition tests on the recovered resin are shown in the following table:

Per Cent Loss in Weight at End of :c Hours Heating at 325 F.

Control 8. 1 l0. 8 16.6 2.0% stabilizer concentration" 0. 2 0. 7 1. 8 0.6% stabilizer concentration 0. 7 1. 5 2. 9

(Latices coagulated with methanol) Example VII A run was made to demonstrate the shortstopping effect which sodium sulfide provides in an olefin-sulfur dioxide resin polymerization. The following recipe was employed:

Parts by weight l-butene 1 46.7 Sulfur dioxide 88.3 Lithium nitrate (catalyst) 0.50

Water 180 Maprofix MM (sodium lauryl-sulfate wetting agent) Shortstop, sodium sulfide Reaction temperature 30 C.

The polymerization was started and allowed to proceed for 50 minutes. At the end of this period the polymerization was interrupted and a sample removed and the per cent conversion determined. The conversion was found to be 48.2%. The shortstop was added at this point and the polymerization was allowed to continue for an additional 6 hour period. The conversion was again determined and found to be 48.2%. The shortstop completely prevented further polymerization after its addition to the reaction recipe.

Example VIII A resin was prepared according to the following recipe:

Parts by Weight Conditions: Stainless steel autoclave reactor. Temperature: F.

Time: 11 hours.

Conversion: 98%.

Commercialbutene as described herein.

The 'resin was prepared from the latex and dried according to the conventional procedure. The stabilizers indicated in the table below were added and the per cent decomposition was dedecomposition'of'the stabilized and unstabilized resin is shown in the following table:

Per Cent Decomposed at 467=|=2 F.-

termined at 325 F. (Latex coagulated with 5 Stabirze magnesium sulfate.) 1 r hr. 1hr. 3111s.

gggzgy g m $Z%tti fi fi :::33:1:::::::::::::::::: ii? iii? it? ihissdfififffitdifiiiitilts?353532352?5311 3122it? mortan- Remaining treatment was same as control. g; n 1(1); Reasonable variation and modification are pos o 5955mm sible within the scope of the foregoing disclosure and the appended claims to the invention, the med Wham" essence of which is that the addition of elemental sulfur or inorganic sulfides to an olefin-sulfur Example IX dioxide resin results in the production of a thermally stable resin and that these agents will A cyclohexene-sulfur dioxide resin was pregag gf i rf polymenzatlon pared according to the following recipe' 1. In the process of producing a stable olefin- Charge; Parts by weight, sulfur dioxide resin the step which comprises ad- Cyclghexene 56,8 mixing a material selected from a group consist- 50 78.2 ing of elemental sulfur and an inorganic sulfide H2O 180.0 with said resin during its preparation. Maprofix MM 1.00 2. In the process of producing a stable olefin- NH4NO3 0.50 sulfur dioxide resin the step which comprises admixing a material selected from a group consisting of elemental sulfur and an inorganic sulfide Conversion: 88 7% of cyclohexene charged. With an acid latex of said resin.

3. In the process of producing a stable olefin- The resin was coagulated by adding methanol sulfur dioxide resin the step which comprises to the stirred latex. The resin was recovered adding a material selected from a group consistby filtering, washing twice with distilled water, ing of elemental sulfur and an inorganic sulfide and drying in an air draft oven for 24 hours at to the polymerization step at a predetermined 130-140 F. The decomposition for the control stage of the polymerization reaction thereby and stabilized resins are shown in the following stopping the polymerization reaction and protable: ducing a thermally stable resin.

4. The process of claim 1 wherein the material is elemental sulfur. Per Cent Degomposed 5. The process of claim 1 wherein the mate- Smbmzer 25:3 rial is hydrogen sulfide.

6. The process of claim 1 wherein the matea 34 3 rial is ammonium sulfide. Nonewontml) 3 8 6 3 15 3 7. The process of claim 1 wherein the mate- 2% sulfur .'IIIIIIIIIIIIIIIIIIIIIII 119 3:3 814 rlal is barium Sulfide- 8. The process of claim 1 wherein the mate- Dispersed sulfur in Orvus solution; added this solution to rial]- is sodium Sulfidetantrastress:assassins asses-s process of Ola-1m 1 wherein the matesulfate wetting agent. r1911 15 a 13m Sulfide- 10. A thermally stable olefin-sulfur dioxide resin composition comprising an olefin-sulfur di- Elample X oxide resin having incorporated therewith as stabilizing agent a material selected from the fbutadiene'smfur {fioxide resm was prepared group consisting of elemental sulfur and an inorusing the following recipe: game lfide Part by weight mposition of claim 10 wherein the Charge; stabilizing agent 15 elemental sulfur.

1 3 butadiene 46.7 The t on of claim 10 wherein the 333 ing agent is hydrogen sulfide. H2O 130.0 13. he composition of claim 10 wherein t Mapr fix MM 21m ili in ag nt is ammonium sulfide. NH4NO3 0.50 e mp siti n of claim 10 wherein the V stabilizing agent is barium sulfide. Reaction temperature: 30 C. 15. The composition of claim 10 wherein the i e sio f l d0% ?f butadiene. stabilizing agent is sodium sulfide.

7 16. The composition of claim 10 wherein the The latex was totally coagulated at the end of stabilizing agent is atin sulfide. the reaction period, and consequently no coagu- .17. In a method for producing a stable heterolant was added. The resin was filtered, washed polymeric resin, formed by the interaction of three times with distilled water, and dried in an sulfur-dioxide and an unsaturated organic maair draft oven at 130-140" F. for 24 hours. The terial, in which the unsaturation is between tw adjacent carbon atoms and which will polymerize with sulfur-dioxide to form said resin, the improvement which comprises admixing a material selected from the group consisting of elemental sulfur and an inorganic sulfide with said resin during its preparation.

18. A thermally stable heteropolymeric resin, formed by the interaction of sulfur-dioxide and an unsaturated organic material, in which the unsaturation is between two adjacent carbon 10 atoms and which will polymerize with sulfurdioxide to form said resin and havin incorpo rated therewith as a stabilizing agent a material selected from the group consisting of clemental sulfur and an inorganic sulfide.

WILLIE W. CROUCH. JOHN F. HOWE.

No references cited. 

1. IN THE PROCESS OF PRODUCING A STABLE OLEFINSULFUR DIOXIDE RESIN THE STEP WHICH COMPRISES ADMIXING A MATERIAL SELECTED FROM A GROUP CONSISTING OF ELEMENTAL SULFUR AND AN INORGANIC SULFIDE WITH SAID RESIN DURING ITS PREPARATION. 